9 Best Tankless Electric Water Heater of 2026 For Endless Showers

1

18kW Tankless Water Heater Electric, ORBEK Instant On Demand Hot

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  9.2
• Brand
  Orbek

Key specs2

Electrical Demands

• 2 x 40A double-pole breakers
• 2 sets of 8 AWG copper wires
• 150A minimum main service panel

Flow Rate Capacity

Up to 4.17 GPM for 2 to 3 fixtures

Pros & cons42

Pros

• Delivers up to 4.17 GPM to supply 2 to 3 fixtures at the same time
• Modulates heating power 20,000 times per second to hold water within 1 degree F
• ETL listed safety system includes dry-heating and water leakage protection
• Standard 3/4-inch NPT water connections match common residential supply lines

Cons

• Requires two dedicated 40-amp double-pole breakers and two sets of 8 AWG wire
• Demands a household circuit breaker panel rated at 150 amps or greater

2

14kW Tankless Water Heater Electric, ORBEK 240 Volt On Demand

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  9.2
• Brand
  Orbek

Key specs2

Breaker Configuration

1 x 60A double-pole breaker with 6 AWG wire

Plumbing Port Size

1/2-inch NPT water connections

Pros & cons42

Pros

• Provides up to 3.38 GPM of on-demand hot water for 2 to 3 points of use
• Runs on a single 60-amp double-pole breaker rather than multiple circuits
• ETL certified build features water-electricity separation to reduce scaling
• Equipped with a digital LED screen for monitoring current water temperature

Cons

• Uses 1/2-inch NPT connections which may require adapters for 3/4-inch home lines
• Requires thick 6 AWG wiring and a minimum 150-amp household electrical panel

3

NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane

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  9.0
• Brand
  Rinnai

Key specs2

Fuel Type & Capacity

Natural gas or propane, up to 11.1 GPM

Installation Notice

Requires dedicated gas fuel lines, adequate venting, and professional installation rather than household electrical hookups.

Pros & cons43

Pros

• High-capacity output delivers up to 11.1 GPM to feed up to 7 fixtures at once
• Smart Sense technology automatically operates on either natural gas or propane
• Condensing design achieves an efficient 0.98 Uniform Energy Factor rating
• Versa Vent system allows for either indoor direct venting or outdoor placement

Cons

• Fueled by natural gas or propane rather than a standard electric household hookup
• Substantially heavier at 55 pounds and requires professional gas-line installation
• Outdoor vent cap and Wi-Fi control module must be purchased separately

4

EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240

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  8.6
• Brand
  EcoSmart

Key specs2

Target Application

Point-of-use, small sink, or single fixture

Flow Rate Range

1.3 to 3.1 GPM depending on inlet water temp

Pros & cons42

Pros

• Delivers 1.3 to 3.1 GPM designed specifically for point-of-use or low-flow sinks
• Compact wall-mount design measures only 11.5 by 8 inches to save cabinet space
• High 99 percent thermal energy efficiency eliminates standby tank heat loss
• Lifetime warranty covers the heat exchanger, heating element, and electronics

Cons

• High 54-amp draw requires dedicated 60-amp circuit wiring for a single fixture
• Flow capacity is insufficient for running simultaneous showers in cold climates

5

Rheem 18kW 240V Tankless Electric Water Heater, Gray

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  8.6
• Brand
  Rheem

Key specs2

Plumbing Port Location

Bottom 3/4-inch NPT water connections

Heating Element Build

Dual copper immersion elements are field-serviceable for easier long-term maintenance.

Pros & cons42

Pros

• Provides up to 4.4 GPM on demand to power multiple fixtures in moderate climates
• Dual copper immersion elements are durable and field-serviceable for easier upkeep
• External digital control provides thermostatic regulation within 1 degree accuracy
• Bottom 3/4-inch NPT fittings align directly with standard residential pipe runs

Cons

• Specific circuit breaker and wire gauge requirements are omitted from the listing
• Needs careful panel verification to confirm adequate spare amperage before setup

6

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

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  8.6
• Brand
  Rheem

Key specs2

Electrical Service Needs

• 3 x 40A double-pole breakers
• 3 sets of 8 AWG copper conductors
• Minimum 200A main service panel

Temperature Control Range

80°F to 140°F in 1-degree increments

Pros & cons42

Pros

• Produces up to 5.9 GPM to easily handle multiple simultaneous hot water demands
• Digital thermostat allows adjustments between 80 and 140 degrees Fahrenheit
• Self-modulating power regulation balances electricity draw against water flow
• Compact 18.25 by 14.5-inch footprint mounts on walls to reclaim floor space

Cons

• Requires three 40-amp double-pole breakers occupying six panel spaces
• Needs three runs of 8 AWG copper wire and a minimum 200-amp main panel service

7

Electric Tankless Water Heater WINTEMP 27kW 240V, Whole House Hot

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  8.6
• Brand
  WINTEMP

Key specs2

Smart Connectivity

Wi-Fi mobile app control and LED digital display

Whole-Home Electrical Specs

• Max draw of 113 amps at 240V
• 3 x 40A double-pole breakers
• Recommended 250A electrical panel

Pros & cons42

Pros

• Powerful 27kW output delivers up to 6.5 GPM for 2 to 4 simultaneous usage points
• Built-in Wi-Fi enables remote water temperature adjustments from a smartphone
• ETL certified safety suite protects against dry-fire, leakage, and overheating
• Backed by a 2-year manufacturer return and exchange warranty

Cons

• Pulls up to 113 amps at peak load, requiring a 250-amp household service panel
• Demands three dedicated 40-amp double-pole breakers and three 8/2 AWG cable runs

8

Rheem 11kW 240V Tankless Electric Water Heater

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  8.2
• Brand
  Rheem

Key specs2

Service Panel Compatibility

Works with standard 100A minimum service panels

Circuit Setup

1 x 50A double-pole breaker with 8 AWG wire

Pros & cons42

Pros

• Compact 7-pound chassis installs in tight spots while delivering up to 2.68 GPM
• Operates on a single 50-amp double-pole breaker with an entry 100-amp main panel
• Digital thermostatic dial adjusts output from 80°F to 140°F in 1-degree steps
• Modulates electrical power in real time to match household water demand

Cons

• Output of 2.68 GPM limits simultaneous fixture use during cold winter months
• Cannot supply whole-home hot water demand for larger multi-bathroom households

9

Westinghouse 11kW 240V Tankless Water Heater Electric, Up to 2.6

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  -
• Brand
  Westinghouse

Key specs2

Voice & Smart Control

Compatible with Alexa, Google Home, and mobile app

Flow Activation Threshold

Activates heating at 0.4 GPM flow rate

Pros & cons42

Pros

• Smart Wi-Fi connectivity supports voice control through Alexa and Google Home
• Sensitive 0.4 GPM activation rate triggers instant heating on low faucet flows
• Connects using a single 50-amp double-pole breaker and 8 AWG wiring drawing 46A
• IPX4 water resistance and ETL certification provide multi-layer protection

Cons

• Maximum 2.6 GPM capacity cannot support running two showers at the same time
• Uses 1/2-inch NPT water connections which may require adapters for 3/4-inch pipes

Last update on 2026-09-25 / Affiliate links / Images, Product Titles, and Product Highlights from Amazon Product Advertising API

Can an existing electrical panel handle a tankless electric water heater?

It depends on your panel total service amperage and available breaker slots. High-capacity electric units pull significant continuous power when heating water. For example, a 27kW unit draws up to 113A and requires three 40A double-pole breakers. Medium options like an 18kW model require two 240V/40A two-pole breakers paired with two sets of 8 AWG wires, while a 14kW unit needs one 240V/60A two-pole breaker and 6 AWG wiring. Before purchasing, verify your breaker box has physical space and adequate service capacity to support these dedicated circuits without tripping the main breaker.

Is an 11kW electric tankless water heater enough to run a shower?

Yes, an 11kW unit can supply a single shower if household fixture demand is modest. An 11kW heater provides between 2.6 GPM and 2.68 GPM, which is capable of supporting simultaneous use across one shower and two sinks. In colder regions where incoming groundwater temperatures drop significantly, flow rates may need to be dialed back to maintain high shower temperatures. Homes running multiple showers simultaneously will require larger units rated between 18kW and 27kW.

How many fixtures can run simultaneously on higher-wattage electric heaters?

Units rated from 18kW to 27kW can support multiple hot water outlets at once. An 18kW model delivers up to 4.17 GPM, providing enough on-demand hot water for two to three points of use while maintaining temperature stability within 1 degree Fahrenheit. Stepping up to a 24kW system provides up to 5.9 GPM, and a 27kW configuration delivers up to 6.3 GPM to handle whole-home demands across multiple bathrooms, kitchen faucets, and appliances.

What size plumbing connections do tankless electric water heaters require?

Connection dimensions depend directly on the flow capacity of the unit, typically using either 1/2-inch or 3/4-inch NPT fittings. A 14kW model often utilizes 1/2-inch NPT water connections, whereas an 18kW unit upgrades to 3/4-inch NPT fittings to accommodate higher water volume. Matching the water heater ports to your existing home supply lines ensures proper flow and prevents unnecessary pipe adapters during installation.

How much space does switching to an electric tankless water heater save?

Switching from a traditional storage tank clears out significant floor space in basements and utility closets. Compact models like an 11kW unit measure just 11.5 by 8 by 3.75 inches, making them roughly 90 percent smaller than conventional tank cylinders. Even higher-output 18kW units measure around 18.5 by 14.5 by 3.5 inches, mounting flush against the wall so you can reclaim valuable living or storage areas.

Can electric tankless water heaters be installed outdoors?

Most electric tankless models are built exclusively for indoor wall mounting and require complete protection from rain, freezing temperatures, and moisture. If your project involves an exterior rinse station or pool cabana, verify enclosure ratings or consider a dedicated tankless water heater for outdoor shower installation designed for exterior conditions. For home plumbing networks, keeping the heater indoors close to primary fixtures reduces heat loss and delivers hot water much faster.